An optical network uses optical signals to communicate information among the nodes of the network. This information often includes both data (e.g., a file that is being downloaded, packets carrying voices of a phone call, or the contents of a webpage) and signaling (e.g., commands or messages between nodes containing status or setup information). In some optical networks the data may be transferred using a data channel (e.g., a datalink) while the signaling is communicated using a control channel. The connections that transmit the data and signaling may be set up using a variety of different protocols. One such protocol often used in optical networks is Generalized Multiprotocol Label Switching, also known as GMPLS. The control plane of GMPLS is mainly designed for establishing connections within mesh networks using the concept of label swapping. Unfortunately, GMPLS has some shortcomings when it comes to establishing connections within Multiplex Section-Shared Protection Ring (MS-SPRing) or Bi-directional Line Switched Ring (BLSR) networks. For example, every add or drop to or from the ring needs to have a backup add or drop path in order to provide protection from node or link failures.
When determining how messages are to be sent between nodes, typically two paths are determined, a primary path and a secondary path. The secondary path provides backup should the primary path fail. In some optical networks, such as BLSR or MS-SPRing networks, resources such as links or nodes used by the primary path can be reused by the secondary path. However in other optical networks, such as mesh or Uni-directional Path Switched Ring (UPSR) networks, there needs to be complete diversity among the nodes and links used by the primary and secondary paths.
In a multilayer network, such as a network made up of different sub-networks and/or technology, it may not be possible for a lower-layer to effectively communicate status/connection information to the higher layer. As a result, the primary and secondary paths are typically determined manually or by separate management components.